The present invention generally relates to quick-motion reproducing systems in rotary recording medium reproducing apparatuses, and more particularly to a quick-motion reproducing system in a rotary recording medium reproducing apparatus, wherein a reproducing element is always shifted to an adjacent track at a position corresponding to a vertical blanking period of a recording video signal or at a position in the vicinity of the vertical blanking period position.
A new information signal recording and/or reproducing system has been proposed in a U.S. patent application Ser. No. 785,095 entitled "INFORMATION SIGNAL RECORDING SYSTEM" filed Apr. 6, 1977, now U.S. Pat. No. 4,331,976, in which the assignee is the same as that of the present application. According to this proposed system, the recording system forms pits in accordance with the information signal to record the information signal along a spiral track on a flat rotary recording medium (hereinafter simply referred to as a disc), without forming a groove therein. In the reproducing system, a reproducing stylus traces over along this track to reproduce the recorded information signal in response to variations in the electrostatic capacitance formed between the reproducing stylus and the disc.
In this system, since no grooves are provided on the disc for guiding the reproducing stylus, it becomes necessary to record pilot or reference signals on or in the vicinity of a track of the information signal such as a video signal, on the disc. Upon reproduction, the reference signals are reproduced together with the video signal. Tracking control is carried out so that the reproducing stylus accurately traces along the track in response to the reproduced reference signals.
By use of this previously proposed system, there is no possibility whatsoever of the reproducing stylus or the disc being damaged, since the recording track has no groove. The reproducing stylus can trace the same portion of the track repeatedly many times, whereby a special reproduction such as still, slow-motion, or quick-motion reproduction becomes possible.
Thus, in a U.S. patent application Ser. No. 4,813 entitled "SPECIAL REPRODUCING SYSTEM IN AN APPARATUS FOR REPRODUCING VIDEO SIGNALS FROM A ROTARY RECORDING MEDIUM" filed Jan. 19, 1979, now U.S. Pat. No. 4,340,907, in which the assignee in the same as that of the present application, a special reproducing system in a disc reproducing apparatus was proposed which is capable of performing a special reproduction in which a picture having a motion different from that upon normal reproduction is obtained in an excellent manner.
The special reproducing system comprises a reproducing element for tracing the track of the disc and picking up the recorded signal, a tracking control mechanism for operating in response to kick pulses applied thereto to cause the reproducing element to shift to an adjacent track turn of the spiral track, and a kick pulse generating circuit for generating kick pulses with timings corresponding to the vertical blanking period positions of the recorded video signal, where the kick pulses are of a number corresponding to the number of operational modes for carrying out a special reproduction differing from normal reproduction at every rotational period of the disc, and supplying the kick pulses to the tracking control mechanism. The reproducing element is shifted to the adjacent track turn within the vertical blanking period of the recorded video signal, by the tracking control mechanism responsive to the kick pulses.
Accordingly, the noise introduced when the reproducing element moves to an adjacent track does not appear in the picture, and a special reproduction such as still reproduction, slow-motion and quick-motion reproduction in the forward direction, and normal-speed, slow-motion, and quick-motion reproduction in the backward direction, can be performed in which a fine picture is obtained.
In the above disc, a video signal of four fields are normally recorded for one track turn. Hence, the vertical synchronizing signal is recorded at four positions for one track turn. In the above previously proposed system, the maximum number of times the reproducing element is shifted to an adjacent track during one track turn is four. Thus, the maximum quick-motion speed in the above system is quintuple-speed.
If a quick-motion reproduction faster than the quintuple-speed reproduction is to be performed in the above system, the reproducing element must be shifted to an adjacent track at an intermediate part of the video information signal, at positions other than the vertical synchronizing signal position within each field. For example, especially during a high-speed quick-motion reproduction, the reproducing element is mostly shifted at intermediate parts of the video information signal. However, when the reproducing element is shifted at the intermediate parts of the video information signal, noise is introduced in the reproduced picture. This noise increases as the speed (multiplicity number) of the quick-motion reproduction is increased, and the reproduced picture will contain undesirable and noticeable noise.